<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<body>
<form action="login" method="post">
  <label>用户名：<input type="text" name="username"></label><br>
  <label>密码：<input type="password" name="pwd"></label><br>
  <button type="submit">登录</button>

</form>
<a href="welcome">测试：未登录则重定向回本页</a>
</body>
</html>